In recent years, the number of various games using video package soft and computer graphics has increased with the proliferation of new hardware. Consequently, there is a demand for displays which vary according to the place and situations in which software is enjoyed. Such displays are used in home television receivers, projectors, portable LCD (liquid crystal display) television receivers, virtual reality HMDs (head-mounted displays) and so on.
One such hardware system which has been proposed is an information transmission system for transmitting video images, audio sound and computer data (see commonly owned U.S. Pat. No. 4,896,209, which was based on Japanese Patent Laid-Open Gazette No. 63-197189). This information transmission system, described in detail below with reference to FIG. 7, may be installed in a vehicle, vessel or airplane in order to provide various information to and from a user, such as a passenger. The information provided to a passenger includes recorded audio and video signals. stick or the like. Using the I/O unit 25b, one may select movies, music, sound volume adjustment, or, if installed in an international-line airplane, proposed duty-free articles. Generally, the selection display apparatus 25 may be mounted on the back of a seat, for example, in such a way that a passenger can watch the monitor 25a and interact with the system with the I/O unit 25b.
One drawback with such a system is the size of the monitor is limited by the area on which the monitor is located. Another drawback is the lack of privacy afforded by use of such a monitor in a crowded viewing area, such as in an airplane. Yet another drawback relates to the image provided by a single image plane.
In order to eliminate at least some of these drawbacks, utilization of a head-mounted type display apparatus is herein described. An optical system for a head-mount type display apparatus is shown in FIG. 8. In this drawing, there is shown a light source 30, a cover 31 having an inner side which reflects light, an LCD panel 32, a reflecting plate 33 for reflecting the light transmitted through the LCD 32, a lens 34 and a viewing point 35. The optical system shown in FIG. 8 may be provided for both the left and the right eyes.
In the optical system of FIG. 8, a video signal is supplied to the LCD 32, and the light from the light source 30 is reflected from the cover 31 incident to the LCD 32. The light penetrating through the LCD 32 is reflected from the reflecting plate 33 into the lens 34 which forms an image at the viewing point 35. Thus, the user can see the video image displayed on the LCD 32 as if he watched the image on, for example, a 33-inch type large screen.
The head-mount type display apparatus mentioned above is of the so-called direct-viewing type. Light from the light source 30 is incident to, and penetrates through the LCD 32. It is then reflected from the reflecting plate 33 and is focused by the lens 34 to form an image at the viewing point 35. As a result, it is necessary that both left and right LCDs be center- and focus-adjusted. This need for multiple adjustments proves inconvenient for a user. In addition, the image of the peripheries of the LCDs 32 are seen by the user and thereby interferes with the image to be projected.